Content uploaded by Gregory S. Wolfe
Author content
All content in this area was uploaded by Gregory S. Wolfe on Mar 14, 2015
Content may be subject to copyright.
OCULAR MANIFESTATIONS OF ADULT-ONSET MYOTONIC MUSCULAR DYSTOPHY
Frank J. Kuchera, OD1,2, Gregory S. Wolfe OD, MPH, FAAO1,2
Southern Arizona VA Health Care System1, Southern California College of Optometry2
ABSTRACT:
A 55 year-old Caucasian male presents for a comprehensive eye examination, and found to have a polychromatic cataract, macular retinal pigmentary epithelial changes, and peripheral retinal findings characteristic of Myotonic
Dystrophy. Additionally, the patient presented with many classic systemic characteristics of Myotonic Dystrophy, such as, myotonic (mournful) facies, myotonia on hand shake, frontal baldness, left proximal arm weakness,
dysphagia of oropharyngeal phase, shortness of breath, and an abnormal electrocardiogram. Adult-onset Myotonic Dystrophy is a rare form of muscular dystrophy affecting 1 out of every 8000 Caucasians worldwide. An
unstable trinucleotide repeat in the DMPK1 gene (Myotonic Dystrophy protein kinase), on chromosome 19q13.3, is the mechanism of the disease, and the gene’s transmittance is autosomal dominant with variable penetrance;
therefore, genetic counseling is recommended. Decreased visual acuity in patients with Myotonic Dystrophy is generally attributable to cataract formation and rarely due to macular disruption of the RPE; however, an abnormal
ERG b-wave can commonly occur without decreased visual acuity. Clinicians should be aware of both the systemic and ocular manifestations of Myotonic Dystrophy, which my require additional systemic evaluation.
CLINICAL EXAMINATION:
CC: Blurry vision at distance and near with
current spectacles.
POHx: Mild blepharitis OU
PMHx:
Myotonic Muscular Dystrophy
Calculus of gallbladder w/o cholecystitis
Abnormal EKG
Shortness of breath
FMHx: + Myotonic Dystrophy
Medications: None
Gross Physical Examination:
Mournful facial features
Myotonic hand grasp
Short stature
Slow gait
Frontal baldness
Left proximal arm weakness
Dysphagia
Mild bilateral ptosis
BCVA: OD: 20/25+2
OS: 20/25-1
EOM: Full range of motion
External: Mild Ptosis OU
SLE: Unremarkable
DFE:
Lens: 1+ NSC, anterior and posterior
cortical refractile polychromatic
opacities, 1+ PSC, OU
Macula:
OD: Flat, RPE pigment clumping in
arcuate shape inferior to
fovea
OS: Flat, Mild ERM inferiorly
Periphery:
OU: area of RPE hypertrophy
with pigment clumping nasal
and superior
DIFFERENTIAL DIAGNOSIS:
Ocular Findings:
Bilateral ptosis
Myasthenia Gravis
Dermatochalasis
Bilateral 3rd Nerve Palsy
Mechanical
Traumatic
Polychromatic cataract:
DM-related cataract
Hypocalcemia
Retinal pigmentary clumping:
ARMD, or other maculopathies
CHRPE
Choroidal nevus
Systemic Findings:
Muscular Dystrophy
Kearns-Sayre Syndrome
Occulopharyngeal Muscular
Dystrophy
CLINICAL PEARLS
Abnormal polychromatic refractile
lenticular bodies warrant workup for
Calcium-related abnormalities.
Lid ptosis and mournful facial
expression can be pathognomonic for
myotonic dystrophy and require
additional systemic evaluation.
The greatest prevalence of myotonic
dystrophy has been found in the
Caucasian population.
POLYCHROMATIC CATARACT:
Lens epithelial changes:
Related to mutated allele on 19q13.3
Expression of DMPK1 gene (Myotonic Dystrophy protein kinase)
High Ca2+ levels found to lead to cell death
Cytoplasm adjacent to refractile bodies shows high Calcium
Concentration
Clinical considerations for cataract extraction:
Recurrent posterior capsular opacities are very common
following cataract extraction
Remaining epithelial cells have large propensity to undergo
fibroblastic proliferative reactions after cataract removal
Ciliary body atrophy may lead to capsulorhexis contracture
FACIAL PRESENTATION:
Mournful expression
Impaired muscles
of expression
Frontal baldness
Bilateral lid ptosis
Impaired Sternocleido-
Mastoid and
difficulty raising
head
RETINAL PRESENTATION:
50% of patients have
peripheral retinal
pigmentary manifestations
20% of patients have
macular manifestations of
pigmentary mottling
Expression of Myotonic Dystrophy is due to expansion of an unstable trinucleotide repeat in the 3’
untranslated region of the DMPK1 (Myotonic Dystrophy protein kinase) gene on chromosome
19q13.3. Increasing number of unstable CUG repeats in this region of DMPK1 are correlated with
increasing severity of Myotonic Dystrophy expression.
REFERENCES:
Abe, Toshiaki; Sato, Masami; Kuboki, Junko; Kano, Tetsuya; Tamai, Makoto. Lens epithelial changes and mutated gene expression in patients with myotonic dystrophy. British Journal of Ophthalmology. 83(4):452-457, April 1999.
Adamczyk DT, Myotonic Dystrophy. in Marks ES, Adamczyk DT, Thomann KH (eds) Primary Eyecare in Systemic Disease (1995) : Apple & Lange, East Norwalk Connecticut. pp 134-138.
Day JW, Ricker K, Jacobsen JF, Rasmussen LJ, Dick KA, Kress W, Schneider C, Koch MC, Beilman GJ, Harrison AR, Dalton JC, Ranum LPW. Myotonic dystrophy type 2: Molecular, diagnostic and clinical spectrum. Neurology. 60(4):657-664, Feb 25, 2003.
Garrott HM, Walland MJ, Franzco O, Franzco J. Recurrent posterior capsular opacification and capsulorhexis contracture after cataract surgery in myotonic dystrophy. Clinical & Experimental Ophthalmology. 32(6):653-655, December 2004.
Myotonic Dystrophy Foundation. (2010). Multisystemic features of Myotonic Dystrophy. Retrieved on October 28, 2010, from: http://www.myotonic.org/professionals/multisystemic-features
Prosena. (2010). Developing therapies for neuromuscular diseases. Retrieved October 28, 2010, from: http://www.prosensa.eu/hc-professionals/myotonic-dystrophy
Shun-Shin GA, Vrensen GF, Brown NP, Willekens B, Smeets MH, Bron AJ. Morphologic characteristics and chemical composition of Christmas tree cataract. Invest Ophthalmol Vis Sci. 1993 Dec;34(13):3489-96.
SCCO
LOGO
HERE
